Tuberculosis LFA Diagnostic Test
Capstone Project
Tuberculosis was the leading cause of death due to infectious diseases prior to COVID-19 and the area's most heavily impacted are typically low resource settings without the proper laboratory equipment to effectively test for it. With an average of 10 million tuberculosis cases and 1 million deaths yearly, it was evident that a readily available and affordable test is essential to improving clinical outcomes worldwide. The most used methods of testing are not up to par in low-resource settings which inhibits a physician’s ability to treat patients. Tuberculin skin tests (TST) are the most frequently used test with a sensitivity of 59%, requiring two visits to a clinician and a high rate of false positives. Interferon-gamma release assays (IGRA) are inaccessible in settings with high rates of tuberculosis due to their cost and equipment requirements. Consequently, a novel rapid testing device needed to be developed to provide accurate results at a low cost, to be accessible in low-resource areas without electricity or laboratory equipment, and had to be operable without a clinician.
Additional Info
LFA Design Solution
As shown below, negative samples without the ESAT-6/CFP-10 complexed protein proceed from the sample pad to the conjugate pad and throughout the membrane. Without the target antigen, the captured DNA aptamer on the test line does not bind to anything, giving a negative readout. In the presence of a positive sample, the antigen forms a complex with the primary FITC-conjugated detection antibody and secondary sheep AuNP-conjugated antibody, which will bind to the aptamer. Excess secondary AuNP antibody on the conjugate pad will continue to flow to the control strip, which is lined with rabbit anti-sheep IgG antibody to validate flow through the membrane.
